I'd like, however, to go deeper in the problem and read more about technical aspects of signage. Like legibility of a sign/type in low light conditions, what is the relation of the size of a sign post to a human height, etc.

There are some books but would appreciate any recommendations on these.

You might also find a use for many of the essays in W.F.E. Preiser. (1989) Building evaluation. Based on the Symposium on Advances in Building Evaluation: Knowledge, Methods, and Applications, held as part of the Tenth Biannual conference of the International Association for the Study of People and Their Physical Surroundings, Delft, The Netherlands, 1988.

And last, but not least: F. Wilson (1983) A graphic survey of perception and behavior for the design professions.

I found a swack of stuff when I was researching my Masters, but it's a pretty long list.... ;-)

I suggest you also make a point of examining the wayfinding graphics in the Underground and in any other transit system you happen to visit. Unfamiliar systems might be more instructive than ones you know. Some systems are like textbooks in what not to do, and can be instructive from a commonsense point of view. If I'm on a train, in a station, and there's no sign visible, either inside or outside of the train, telling me what station I'm at, then something's wrong. Basic functionality like this is a very worthy starting point, since some systems have yet to achieve it. Sign placement, type sizes, location, traffic patterns, direction, are all more fundamental issues than things like halation and color.

Carl, I'm in London and examining the Tube's visual system every day. It even inspired me for designing a "cover" for on-line design magazine (when you hover over the line's names, letters appear making word Lądek which is Polish familiar name for London).

What I'd like to know more is the whole process of analysis of a city, gathereing all the information, asking questions and then transforming all this to a system. So, the bigger picture first.

Last year in Design Week I've read that London will have new uniform signage system for pedestrians.Do you know any details - who, when..?